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General Category => Weather & Atmospherics => Topic started by: martinastro on November 10, 2009, 11:47:31 pm



Title: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 10, 2009, 11:47:31 pm
From the UKweatherworld....

Synoptic Discussion - Possible Stormy Spell 13th to 16th Nov

Issued 22Z Tues 10th Nov

Considerable discussion already underway regarding possible events for late this week and the weekend, but this thread is kept for the detail synoptic discussion of the developing situation.

The situation is very complicated by the interaction of low level thermal baroclinic waves, a strong upper level jet stream and shortwaves moving across the Atlantic.  Each model run is coming out with different detail, and its quite likely the actual detail will not be known until nearer the time.

The first low or wave depression comes NE on Thursday, this can be traced back to a low coming out of the Eastern Seaboard at present, this low comes NE with some deepening (the low largely stays ahead of the main jet Core and is only partially engaged as it comes NE across the UK.  At the same time the thermal gradient across the Atlantic tightens and moisture in the mid levels is derived from Ex Hurricane Ida currently piling NE across the SE'ern United States.  By Thursday the next wave develops as a weak thermal baroclinic disturbance on the PFJ NNW of the Azores, a very tight thermal gradient will be present with a low latitude 160Knt+ Jet Core located nr 43N across the Atlantic.  This Jet Core moves east and the disturbance crosses on to the cold side of the JEt Core.  There is considerable uncertainty regarding how complex the low will be as it moves NE, Some solutions have hinted at considerable troughing between the baroclinic low and some sort of cold air disturbance to the NW.  It is not clear yet how the two will play out.

Into Friday and the low moves NE deepening rapidly as it moves under the left exit of the propogating westerly Jet Core, The 12Z GFS (and a number of its ensemble) produces an early deepener and turn the low into Ireland as a potent low pressure system (Storm Force 10's/11s in SW Approaches) The 12Z UKMET (upgraded to run at 70 levels from today) preferred a slower deepener and a more complex centre with a tight pressure gradient around the southern end of the elongated low.  The 12Z ECM was similar to the UKMEt but positioning was west of the UKMET. The ECM also had a more complex centre, ironically its earlier solutions had been more akin to the 12Z GFS Operational.   The 12Z FIM was similar to the GFS but further west whilst nearly as deep.  (18Z GFS just seen appears to be slightly less deep than the 12Z Operational but largely within noise range)

The 18Z NAE picks up the embryonic low at T+48 (largely getting its outside area data from the UKMO Global Model) its not suprising therefore its postioning of the low at that timeframe is similar to the GM.  The NAE however does have a deep low over N Ireland on Thursday evening formed from the 1st wave mentioned above.  This may be overdeepening the low a little but it does indicate the highly developmental phase the Atlantic is moving into.  Gales likely up the Celtic and Irish Sea as early as Thursday.

There is clearly a decent risk of severe gales or storm force winds given the strength of the JEt Stream and the very tight thermal gradient, what appears key in the development is the location and depth of the 300mb trough which is coming east to engage the low.  As this trough is currently only over Northern Canada its highly likely we will see considerable chopping and changing as the trough comes east into an area where there is a more plentiful supply of upper air obs.  Aside from the Wind there is a lot of rain to move NE over the next 5 days

even global models are forecasting 40-60mm this could easily be increased by 50% over the exposed hills and mountains to the west and SW.

Another low looks set to move NE on Sunday into Monday - the UKMO Global Model tracking the low from COrk across to Humberside with risk of Gales to the South.

P Blight



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: markt on November 11, 2009, 07:25:14 am
Sounds rough to me - batten down the hatches!


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 11, 2009, 04:26:56 pm
(http://i35.tinypic.com/24boqh3.jpg)

Forecasters Warning

Heavy Rain and Severe Gales

Affecting: Southwest England, Wales, west and northwest England, western Scotland, Northern Ireland and the Republic of Ireland

Valid: 13:00 Friday 13th November to 23:00 Saturday 14th November 2009

This is an Advanced Weather Warning issued by Metcheck at 20:40 on Tuesday 10th November.

A deepening area of low pressure is expected to track north/north-eastwards across western parts of Britain and Ireland during Friday and Saturday, bringing heavy rain and the risk of severe gales.

Greatest concern is currently focused on western Britain and Ireland where the heaviest of the rain and strongest winds are likely to occur.

Rainfall totals of up to 2 inches (50mm) may fall during Friday afternoon and night in places, whilst severe south-westerly gales gusting up to 80mph could affect the southwest during Friday night and Saturday, before affecting other western areas during Saturday.

These conditions will result in hazardous travelling conditions, and some localised flooding may occur in areas where the land is saturated after recent rainfall. In addition, some damage to buildings and trees may occur in the severe gales.

This Advanced Weather Warning will be updated tomorrow, Wednesday 11th November.

Issued by: Paul Barber for Metcheck
---END---


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 11, 2009, 04:29:45 pm
TORRO CONVECTIVE OUTLOOK

Over the next few days, the British Isles are at risk from severe weather, mainly in the form of high winds and heavy rain. Some of the strong winds are likely to be associated with severe convection, and there is a slight risk of tornadoes in a few places.

The first risk, albeit fairly small, will be on Thursday afternoon and evening, as a cold front moves eastwards. There are some indications that across southern and central parts of England and Wales, line convection may develop in a region of reasoble low-level shear...thus, misocyclones may develop, enhancing the chance of strong winds and isolated tornadoes.

A more vigorous set of fronts will cross the British Isles through Friday and Friday night. The cold front and triple point of this system may be areas where convection is possible. With strong winds throughout the atmosphere, changing in direction with height, a few tornadoes may be possible, along with some strong wind gusts. The system will also produce strong winds away from convection too.




Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: brianb on November 11, 2009, 05:05:55 pm
Interestingly, when observing last night I was aware that the sound of the surf battering the shore was much louder than usual ... heavy surf seems to precede storms by a couple of days so I reckon it will be windy on Friday. (Must cut down on the beans...)


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 11, 2009, 05:13:24 pm
A lot saying that the ROI going to bear the brunt of the storm


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 11, 2009, 05:42:57 pm
I could imagine things gettting choppy up there Brian.

Yes, ROI and SW Britain so far are getting the strong winds although heavy rain and convective potental for many. This is from Tony Gilbert...

Pretty much a 'double whammy' with two rounds of activity. The most prolific being Friday night with 120kts 500mb! ...If models remain as is then this could potentially be the strongest convective outlook for 2009

Particular attention is given to the UKMO forecast synoptic charts where a combination of three circulating low pressure zones over the Atlantic funnel some very unstable air from deep down in the Azores as a deep upper trough slides in from the west. Its anomalies like these that make the most interesting outlooks possible!



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 11, 2009, 09:12:25 pm
Model Guidance continues to oscillate between different scenarios with regards the low coming NE Friday Evening through Saturday.  The 12Z GFS has a strong interaction with the shortwave coming east across the Atlantic, effectively locking in the PVA the trough and combining it with the diffleunce of the Left Exit of the 160knt Jet coming towards the SW.  There is a fairly consistent signal for a somewhat elongated low to form in the SW approaches into Friday, as the low latitute baroclinic low combines with the colder air trough to its NW, effectively forming a elongated low pressure system SW of IReland.  What is not clear is as to which of two possible low pressure systems will develop

The 12Z GFS really develops the southern low with an elongated low extending NE, this brings Storm force 10s to the Channel and potential 600m gusts to 70knts through the Channel which post cold front could see surface gusts to 65knts along the Channel.  There is also a swathe of strong winds ahead of the squally cold front which goes through Friday Night with gusts to 60-65mph in places

The 12Z UKMO GM however prefers to develop the northern centre with a low over Kinross vs N Wales in the GFS - The Pressure gradient is therefore not as intense across England and S Wales, the southern centre relaxes as it moves NE whereas in the GFS it is maintained as the main low centre. This is frequently a problem for numerical models with elongated low centres they have difficulty choosing which centre to develop and which not to...  At this stage its difficult to see which will be correct, and in terms of wind rain the two stories are similar - except the GFS has a stronger 2nd bout of wind on Sat. The 12Z GFS Ensemble gives a general indication for WEt and Windy conditions but does not have the required resolution to determine which centre will develop.  As the timeframe nears the NAE and Higher Resolution REgional Models should be able to provide a better steer on the potential development.

Beyond that there are more significant differences as early as T+60 in the vicinity of the Azores, the UKMEt has a slower more developed low which effectively has time to get picked up by another trough and this moves NE as a deepening low early on monday.  The GFS has a much flatter faster feature running NE, the source region is the complex low SW of Bermuda which contain the remnants of Ida, and therefore will be subject to further model differences



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 11, 2009, 09:14:08 pm
(http://i34.tinypic.com/wks46x.jpg)

Storm Forecast
Valid: Thu 12 Nov 2009 06:00 to Fri 13 Nov 2009 06:00 UTC
Issued: Wed 11 Nov 2009 20:17
Forecaster: GATZEN
A level 1 was issued for portions of England and Wales mainly for severe wind gusts and for a lower extend for tornadoes.

SYNOPSIS

A broad trough over Europe moves north-eastward, while warm air advection sets in over western Europe ahead of an Atlantic trough. This is associated with a strong mid-level jet streak spreading into western Europe. At lower level, a strong jet will advect moist air across the Bay of Biscay and the British Isles late in the period. Further east, most of Europe is dominated by dry air masses. Over the Turkey region, rather moist low-level air mass is present in the range of the trough.

DISCUSSION

Portions of England and Wales

Models agree on the development of a strong mid-level jet streak spreading into the northern Bay of Biscay in the evening hours, and strong QG forcing will be present in the warm air advection regime ahead of the surface cold front of low pressure over the Atlantic Ocean. A 25 m/s low-level jet is forecast by latest numerical models leading to strong low-level vertical wind shear, while the low-level mixing ration may reach more than 8 g/kg in the south-western portions of the British Isles. Weak instability is forecast due to differential warm air advection in an air mass characterized by nearly moist-neutral lapse rates. Together with strong linear forcing along the cold front, a shallow line of convection is forecast to develop in the evening hours. North of the mid-level jet, deeper convection will likely evolve cold pools due to melting of graupel and snow, helping the convection to organize. Bowing elements are expected, associated with severe wind gusts and possibly tornadoes in the range of embedded mesocyclones. The convective line will rapidly spread into the North Sea late in the period, where the potential of deep convection decreases due to weaker low-level moisture.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: JohnC on November 11, 2009, 11:31:43 pm
I'm keeping my eye on this ,Martin. Saturday looks good for me ( too much rain tomorrow and Friday) and high tide is at a reasonable time in the afternoon. I'm not sure whether to go to the North Devon coast or the south coast near  Lyme Regis  as the winds will be almost out of the south there - ie. head on, onto land ,whereas at Ilfracombe (N. Devon)  near where I'd go (Hartland Point) it would be a more westerly wind . I don't know enough about how the wind impacts on wave height, maybe someone  can point me in  the right direction.  The seas at both locations are forecast to be 'rough'. The centre of the low as forecast for Friday/Saturday will be close to us and may pass just north of Gloucester. These lows are normally much further north


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 12, 2009, 04:18:31 pm
UKww Weather Warning for Heavy rain and severe gale to storm-force winds


Issued Thursday 12/11/2009 1400BST

Areas affected: Wales, England (with emphasis south of a line Preston-Newcastle-upon-Tyne)

Valid from: 1400GMT Thurs 12th November - 0300GMT Sun 15th November


--------------------------------------------------------------------------------

General evolution:


An area of low pressure with a centre at 970mb 300 miles west of Galway at 1200 Thursday will become complex with several centres in the following 24 hours. One such centre, 980mb, 250 miles SW of co. Kerry at 1200 Friday, comes under the left exit region of a powerful jetstreak Friday into Saturday morning with the result that it deepens to 970mb as it approaches the SW UK, expected just off St Davids Head at 1200 Saturday and clearing into the North Sea early on Sunday. Associated fronts followed by showery troughs will alternate over the UK during the forecast period.


Forecast:
Intense rainfall associated with the first set of fronts, already into SW England, N Ireland and W Wales, will continue to spread N and E through the rest of Thursday. Some very heavy bursts of rain are to be expected with strong and squally winds possible. Rain totals of up to an inch (25mm) are possible and due to the intensity of the rain there could be flooding problems caused by rapid runoff from already saturated ground. Clearer conditions but with squally showers, thundery in places with hail, will follow on Thursday evening and will last until Friday morning when the next frontal rainbands will push up from the south giving a very wet day indeed for southern England and Wales, the rain again very heavy and squally at times. 2-3 inches (50-75mm) can be expected, with the highest totals likely over the Welsh mountains and the moors of the SW: following on from Thursday's rain means that flooding is almost inevitable. This rain clears overnight into Saturday but is replaced by heavy showers and most significantly by severe gale to storm-force winds moving in from the SW and affecting S & W coasts, with gales or severe gales affecting inland S England and Wales. Saturated ground makes trees easier to blow over, and the highest gusts (70-80mph, the latter especially associated with heavier showers) will be sufficient to topple trees, break off branches and cause structural damage. This threat, in addition to flooding and leaves blown in quantity onto the roads, spells out a difficult and at times dangerous period for road users, with some disruption expected.

Issued by JSM for UKww, 1400GMT 12/11/2009



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 12, 2009, 08:26:48 pm
19Z Update

A Potent shortwave upper trough visible on WV imagery and Airmass Imagery lies across Ireland into the SW Approaches, the northern filament of this trough and its assoc PVA has engaged the cold front and developed a cyclonic circulation NW of Malin Head.  This is producing quite strong winds in the circulation, gusts to over 40knts and an active rainband moving east.  The cold front is exhibiting strong Line convection elements with hourly totals confiming the NAE's estimates of up to 10mm in an hour or so across many places as the front comes east.  Some very lively echoes across the South and SE need watching for possible embedded convection this evening with Severe Weather diagnostics indicating a possibility of Tornado's and/or strong convective gusts - more esp a little later as the shortwave moves over the front.  Front is currently waving over SW England with more dynamic rain here for a time, however the back edge of this wave likely to turn very convective later this evening as it moves east with gusts to 50knts + possible in places esp around the South Coast headlands.  Thunderstorms, Hail and Weak Isolated Tornadoes possible. Another 10-20mm possible across the South and SW.  Flood Watches will increase dramatically over the next 24 hrs.

To the SW a very strong Jet stream is located North of the Azores. Models have responded to Midday Aireps which suggested this Jet was 5 knts or so stronger and is now analysed at over 165Knts for the next 24hrs before weakening slightly.  At the same time a active upper trough is sharpening and moving east close to 30W.  Over the next 12hrs the shortwave will engage the frontal zone and a deep elongated low will develop. Initially heavy rain will move NE along the warm front giving a lot more rain across the SW, 75mm is possible over the Moors and Mountains in S Wales perhaps locally more. 

The development of the low tomorrow and tomorrow night has become less diverse in the model solutions with most solutions now forming a deep low SSW of Ireland and moving NE, The NAE produces the deepest centre around 958mbs at T+33 SW of Valentia, and then tracks it NE.  The UKMO and ECMWF are similar in moving a deep low NE close to the ISle of Man as a relaxing low but with a deep pressure gradient to the SOuth, essentially the message from all the major guidance is in agreement on the theme.  The detail is a little elusive with risk of Storm Force winds across the SW Coasts rated at 50% at this time IMO.  Gusts in the unstable air give 70mph + in a few places 50-60mmph inland. These gusts close to 925mb winds which in the cold air momentum could drag the stronger winds down esp in showers. 

The cold front also giving strong winds with a zone of Severe Gales likely ahead of the cold front turning into a squally affair.

At this time the UKMO GM and ECM are probably best guidance, the NAE is over deep at the beginning and then relaxes the centre N little too quickly. The GFS also looks to relax the low a quicker than the ECM/UKMO Mix.

More Trouble early next week with another low coming NE, GFS further NW with this ECM/UKMO a little further SOuth, UKMO rather a different solution confining any strong winds to England. ECM a good compromise between UKMO and GFS at this stage.

its hard to keep up at the moment, there is a lot going on.


-----

Paul Blight
UKww Manager - Education/Warnings


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 12, 2009, 08:41:30 pm
Some vicious weather coming over the next 48hrs especially for sw england its going to be interesting to see how it develops.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 12, 2009, 09:25:24 pm
Some models showing  an even worse storm to slam ROI next wednesday put could change as we all know by now from fridays charts


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 12, 2009, 09:52:09 pm
Check this out! - they even mention that a level 2 is possible for S UK!! - I've never heard of that before for this part of the world.

(http://i37.tinypic.com/10gzigk.jpg)

Storm Forecast
Valid: Fri 13 Nov 2009 06:00 to Sat 14 Nov 2009 06:00 UTC
Issued: Thu 12 Nov 2009 21:22
Forecaster: TUSCHY
A level 1 was issued for parts of the Bay of Biscay, UK, Scotland and Ireland mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

An extensive baroclinic zone has established between 10-40°W and 40-50°N. This region will be the setting for a rapidly developing depression and phase diagrams of numerous model data indicate a warm core seclusion with this feature. Slow forward motion during the rapid intensification stage (until 18-21 UTC) gives way to a more rapid NNE-ward motion during the night hours, as a strong jet ejects out of the base towards the north. At the surface, a cold front pushes eastward, trailing over the Atlantic with a more aggressive propagation over Irlenad, UK and Scotland.

Ridging downstream affects central Euorpe with cold/stable conditions over far east/northeast Europe.


... Bay of Biscay, NW-France, extreme NW Spain and N-Portugal ...

Aforementioned warm seclusion is in full progress west of Irleand and assists in a rapidly strengthening wind field at all levels over the area of interest. In fact, 20-30m/s 0-3km shear does not reflect at all the strength of the overall wind field with 45m/s at 700hPa, increasing to outstanding 65m/s at 500hPa, approaching the Bay during the day from the NW. The increasingly negative tilt of the upper trough axis and the gradually increasing inertial advective wind component along the base of the trough causes overall jet strength to decrease during the evening and night hours, with one stronger branch exiting the area to the north (UK) and a re-developing one along the zonally aligned baroclinic zone over the Atlantic.

Overall synoptic pattern and intense LLJ (40m/s at 850hPa), pumping rapidly mixing/thinning tongue of subtropical air towards the north, probably establishes an extensive warm conveyor belt (WCB), running from extreme NW-Spain/N-Portugal all the way to NW-France and UK. WAA keeps atmosphere neutral/stable with moist adiabatic ascent and there is no risk for deep, moist convection. However, a region for isolated, deep convection could evolve along the back (west side) of the WCB, as the cold front and somewhat drier/cooler
upper-level air approaches from the west. Another feature, which fosters this scenario is the split front appearance in forecast model data/cross sections of the cold front itself. Given the magnitude of the LL wind field, at least a level 1 was issued due to the limited coverage of showers/very isolated thunderstorms. The main risk of this activity will be confined to the NW-Bay, NW-France and extreme SW-UK. Overall environment with low ELs and weak updrafts is hostile enough for not even issuing a low probability thunderstorm area.

... United Kingdom, Scotland and Ireland...

The outlook for UK turns out to be even more complex in respect of the degree of thunderstorm coverage. The WCB with more stratiform rain ought to keep the atmosphere very moist and stable for vertical ascent, so the main focus for convection arises during the evening hours, when the cold front draws near from the west. Overall set-up looks promising for a flare-up of convection during the cold front passage over S/central UK as surface cold front gets topped by WAA above 5-6km AGL with aforementioned 65m/s streak at 5km covering SW-UK during the sunset-midnight hours. Despite the unfavorable placement of the front beneath the indirect thermal jet circulation, overall diffluent upper streamline pattern and left exit of a streak at roughly 3km, crossing SE-UK during that time, point to adequate conditions for low-topped convection. Forecast soundings indicate some LL CAPE release and the possibility for storms to evolve in roughly 30-40m/s 0-5km shear (even stronger, if deeper convection verifies). Speed and directional shear, low LCLs and NE-ward racing vorticity lobe create a favaorbale environment for a strongly forced convective line (LEWP-type) with damaging wind gusts and tornadoes possible. Model discrepancies are still high, so new model data has to be evaluated to determine the final severe weather risk. A coarse level 1 was issued, but if the forced line with embedded thunderstorms verifies, a level 2 may be needed.

Another area of concern arises over SE-Ireland and east/northeastwards at 15 UTC onwards, as the triple point of the warm/cold front and occlusion approaches from the SW. Enough instability for stronger and more persistent updrafts and forcing/shear in the extreme range indicate a severe wind gust and tornado risk and an isolated strong tornado event can't be ruled out. This risk spreads northeastwards, affecting S-Scotland thereafter. Decreasing instability onshore may be delayed by the left exit of the 50-60m/s mid-level streak and hence the level was expaned well towards the north.

... South of Ireland and extreme W/SW-UK 21 UTC onwards ...

The intensification of the depression just to the WSW of Ireland will be already in the end pahse and occlusion starts. GFS and ECMWF are in line with the overall scenario, whereas the rest of the model pool is still oscillating around their solution. For now, we stick with the American/European model solution, which sounds quite reasonable, as both models had the most persistent scenario during the past few runs. A back-bent occlusion starts to wrap around the center beneath a pool of drier high-tropospheric/low stratospheric airmass, covering the center of the depression. A rapidly intensifying sting-jet event is forecast to unfold at roughly 21 UTC onwards, affecting the offshore areas south of Ireland. Model output forecast wind speeds indicate gusts in excess of 35-40m/s, which sounds reasonable, given 40-45m/s at 850hPa and a well mixed postfrontal airmass. This evaporatively cooled air is not favorable for deep convection and therefore the damaging wind gusts risk is not reflected in our risk level forecast, but damaging and potential life-threatening wind gusts in excess of 35m/s affect SW-UK after 03 UTC and spread eastwards thereafter.

Just for the sake of completeness, the last similar event (although not comparable in respect of forcing and wind speed) was severe extratropical cyclone Klaus over the far S-Bay of Biscay. A few thunderstorms occured in a similar environment offshore and onshore, so the risk for isolated showers/thunderstorms can't be ruled out completely. An upgrade may be needed, if this concern increases.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 12, 2009, 10:07:30 pm
Wow thats some read!!!!! :o


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 12, 2009, 10:41:00 pm
Bad flash floods in Cork yesterday...

http://www.youtube.com/watch?v=JJ33tNoO_sk

Credit: Irish Weather Network.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 02:55:32 pm
(http://i38.tinypic.com/2ch6vkm.jpg)

TORRO TORNADO WATCH 2009/009

A TORNADO WATCH has been issued at 13:20GMT on Friday 13th November 2009

Valid from/until: 13:20 - 14:00GMT on Friday 13th/Saturday 14th November 2009, for the following regions of the United Kingdom & Eire:

Parts of (see map)

All of England and Wales

S Scotland

Eire
N Ireland

THREATS

Tornadoes; wind gusts to 80mph; hail to 15mm diameter; CG lightning

SYNOPSIS

Rapidly deepening low exhibiting warm-seclusion characteristics will push an active set of fronts across the British Isles today and tonight, and then an active occlusion/trough eastwards across southern parts tomorrow.

Convection is currently occurring in the strong warm advection regime near SW England, and will spread northwards this afternoon and evening across western parts. This brings the risk of strong winds and hail, and CG lightning, but also a slight risk of tornadoes - the risk extending along the south coast and perhaps into other areas of S England this afternoon along the northward moving front.

Overnight tonight a strong cold front will surge eastwards bringing squally wind gusts of up to 65mph inland and 70mph on the south coast, some aided by convection. In addition, a chance exists for a few tornadoes, perhaps strong. This risk is mainly for central and southern England and Wales.

Later tonight and through tomorrow morning, an active occlusion will be pushed eastwards across England and Wales, again especially across southern parts. Some severe convection may accompany this, bringing wind gusts of up to 80mph in exposed SW'ern parts, and 60-70mph elsewhere. A risk of tornadoes exists with this too, especially if convective lines develop.

The purple area on the WATCH map is the region deemed most at risk from severe winds - a dangerous situation as inland gusts this high are rare in southern Britain.

Forecaster: RPK


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 04:55:12 pm
Quite a set up so and so

Very nasty looking skies here atm very dark


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 05:11:11 pm
ESTOFEX have a level 2 out for S. UK!!!, first time I've ever seen this. Level 1 area also extended across much of Ireland and UK.

(http://i37.tinypic.com/2r4mu01.jpg)

Forecast Update
Valid: Fri 13 Nov 2009 17:00 to Sat 14 Nov 2009 06:00 UTC
Issued: Fri 13 Nov 2009 16:55
Forecaster: TUSCHY
A level 2 was issued for the western English Channel and extreme SW-UK mainly for severe wind gusts and to a lesser extent for tornadoes.

A level 1 was issued for Ireland, Scotland and United Kingdom mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

Please refer to the main outlook, issued at Thu 12 Nov 2009 21:22.


DISCUSSION

... Parts of the Bay of Biscay, the English Channel and UK ...

Latest remote-sensing data reveals an active warm conveyor belt (WCB), spreading NE-wards. Wave-like appearance in high resolution visible data and recently reported thunderstorms, embedded in this WAA regime, hint on CSI release, responsible for embedded line of enhanced convection (thunderstorms). Despite rapidly increasing wind fields, this activity of thunderstorms over SW/S-UK remains elevated in nature although not much BL modification is needed for near surface based activity. The main risk ought to be a severe wind gust risk although even an isolated tornado event can't be ruled out, given favorable backed wind profile and near zero CIN. Therefore, the low probability thunderstorm area was expanded significantly in all directions, to include active WCB, but also the anticipated more active backside of this belt due to the approaching cold front. Strong dry slot continues to punch northwards, a bit further west than what was expected yesterday. Enhanced convection is just about to reach Ireland, so the level 1 was expanded towards the west. Severe wind gusts and isolated tornadoes are possible over Ireland (most likely over SE/E-Ireland), W/central UK and most parts of Scotland. Degree of LL shear, increasing LL CAPE west of the WCB and low LCLs still indicates a chance for a strong tornado event, especially along the coast, where onshore swashing CAPE and shear overlap.

An upgrade was performed for the time-frame 00-06 UTC, although the severe risk continues later-on. Wrap-around moisture and already developing intrusion of dry high-level air just south of the warm core seclusion point to a developing sting jet event and cloud top loops show a warming trend along this spot. Despite a gradual decrease of deep convection in this area, a broad swath of deep convection is approaching SW-UK from the southwest. Forecast soundings and 06/12 UTC GFS runs still indicate an overlap of some CAPE (maximized over SW-UK, over the English Channel and over extreme NW-France). The overlap of 35-40m/s at 850hPa , approaching tongue of the wrap-around moisture and cool mid-levels indicate that not much is needed for damaging wind gusts producing deep convection and therefore a level 2 was issued to reflect the convective component in this concentrated severe wind event. A tornado event is possible along the SW/S-coast of UK and again, a strong tornado can't be excluded.

The most likely scenario will be an eastward racing forced line (EL temperatures below -30°C and beneath the left exit of a 65m/s mid-level streak) with the sting jet pointing into the backside of this line. After the passage of the line, thunderstorm chances most likely decrease over far SW-UK whereas damaging winds keep going. Thunderstorm chances will still be present further north along the W-coast of UK and Scotland also with severe wind gusts and an isolated tornado risk.

... Extreme NW-Spain and extreme N-Portugal ...

Difficult to determine the environment, where current thunderstorm activity is embedded. At the tip of the WCB, a warm and moist inflow beneath eastward spreading cooler mid-level air supports numerous thunderstorms, and conditions remain supportive at least until "landfall" of this warm conveyor belt. In fact, up to 500 J/kg MLCAPE, roughly 100 J/kg 0-3km CAPE, LCLs below 500m, 20m/s 0-1km speed shear and 200-300 m^2/s^2 SRH1 are supportive for tornadic supercells (a strong event possible), next to damaging wind gusts, given 35m/s at 850hPa. Therefore, a level 2 was included. The severe risk will be maximized probably between 17-21 UTC, decreasing rapidly over the Bay due to the clipping of the inflow by the Iberian Peninsula. The risk also decreases to the south along the west coast of Portugal, as shear gradually relaxes.



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Roman White on November 13, 2009, 05:36:22 pm
ESTOFEX have a level 2 out for S. UK!!!, first time I've ever seen this. Level 1 area also extended across much of Ireland and UK.
Mmm... looking forward for any reports  ::)


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 05:44:57 pm
This is fast becoming the most interesting severe weather forecast and event of the year for the UK. The net is buzzing with storm chat. There's a real possibility of a tornado outbreak from this storm. Severe weather warnings appearing everywhere, even for NI for flooding. 74mph gusts already reported at Land's End with thunderstorms moving into the SW coast of Britain. This is from the UKASF...

A very deep area of LOW pressure to the Southwest of the United Kingdom will bring severe weather to parts of the country over the next 24-36 hours. Heavy, slow moving rain, with an increased risk of embedded thunderstorms, will affect parts of England and Wales through the rest of today and tonight. Torrential, persistent rain may lead to local flooding in places. Conditions will be quite favourable for the development of tornadoes, which if they do occur could be moderate in intensity and cause structural damage. Very strong winds will affect southern England and south/west Wales this evening and tonight, with gusts up to 80mph possible in exposed locations. Winds may be strong enough to cause structural, power and transport disruption.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: markt on November 13, 2009, 05:55:18 pm
Tis' pretty wet here in the west mids at the moment, winds not kicked in yet, though i'm sure they will...


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 07:07:20 pm
Heavy rain here now winds have really kicked off now


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 13, 2009, 08:55:33 pm
Yeah Padraig the Republic is getting some very heavy rainfall right now. Dry here with only a slight breeze.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 08:56:41 pm
Reports of flooding and damage in the S of Britain with lightning/possible power flashes and trees brought down through a house, and another incident on a car, the occupants of which were cut free by the firebrigade. Strongest radar echoes at the moment are over Ireland.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 10:46:27 pm
Quite a show over there just had a very squally heavtyish shower if i can put it that way quite strong winds the rain band is well gone now from here ????? i though different


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 10:48:21 pm
The ROI have been getting intense radar echoes now for some time, there's a nasty large persistant white return in SW Ireland (inland) which appears to be rotating when I flick through the Met O radar during the recent updates. I wonder if it's a convective cell rotating?


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 10:53:35 pm
What  I don't understand is that even when the heaviest rain is forecast for the east of the country the west always gets it worse?????


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: brianb on November 13, 2009, 11:02:02 pm
Quote
when the heaviest rain is forecast for the east of the country the west always gets it worse?
Easteners and southerners are soft. The South East of England is making a big fuss over the sort of storm I'd expect to see here three or four times every winter.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 11:02:37 pm
I know what you mean, it's the unpredictable nature of the weather, even the experts get taken by surprise!.

Brian lol, you might get a retaliation on here from someone  :)


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 13, 2009, 11:08:08 pm
I noticed that too Martin looked very interesting, rain moderate here now i wonder if any of that intense rain will come our way in the coming hours, hope so  ;D


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 11:19:35 pm
I hope so to...it's going to be a long night in front of the computer  ;D


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 11:22:41 pm
just had a very heavy but odd shower it stopped and u could here it coming in the distance again


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 11:32:48 pm
Moderate rainfall here, winds picked up for a while then relaxed again. I hope we get those strongers echoes later.

Very interesting radar over S. Britain indicating a possible convective line with LEWP which can produce tornadoes.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 13, 2009, 11:40:16 pm
Incase any readers on here don't know, here's the links to the Met Office radar and sferic (lightning plots) charts.

http://www.metoffice.gov.uk/weather/uk/radar/

http://andvari.vedur.is/athuganir/eldingar/

A LEWP is a Line Echoe Wave Pattern


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 13, 2009, 11:40:46 pm
nasty random bursts of rain here  its going to be a long night

Edit : LEWP that's a new one for me Martin


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 12:33:58 am
Flooding has to be inevitable across western ireland by now some serious echoes there and arent budging


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 14, 2009, 12:40:53 am
Heavy rain here now battering off the conservatory roof!


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 12:49:06 am
Getting interesting, after a lull the radar as intensified over NI with red echoes. Thunderstorms have formed over the coast near Dublin, Padraig watch the sky to your E and NE for flashes.

Tony Gilbert reckons there's a good environment for tornadoes over S. Britain at the moment, in the exact same area as the tornado last week.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 12:54:07 am
Cant see any atm Martin although can see a structure i wonder too far away


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 12:57:47 am
OK, check the sferic link above and see what direction those recent plots are in relation to you. I seen a flash of lightning last night in a clear sky complete with c-g bolt and it was hundreds of miles away to the SW over the Atlantic. If visibility is poor then it won't be so easy. Those showers are turning into storms...some of them anyway. Also, the sferics charts only plot c-gs and not i-c bolts so there could be storms out there that we don't know about.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 01:00:11 am
Outlook for Sat...

(http://i36.tinypic.com/30iur9w.jpg)

Storm Forecast
Valid: Sat 14 Nov 2009 06:00 to Sun 15 Nov 2009 06:00 UTC
Issued: Sat 14 Nov 2009 00:06
Forecaster: TUSCHY
A level 2 was issued for parts of the English Channel and the coastal areas of S-UK mainly for severe wind gusts and to a lesser extent for tornadoes.

A level 1 was issued for most parts of the UK, surrounding the level 2 mainly for severe wind gusts and to a lesser extent for tornadoes.

SYNOPSIS

Extensive cyclonic vortex over far NW-Europe steers numerous disturbances around its fringes, which affect western and N-Europe during the forecast. Ridging over the Mediterranean suppresses convection, whereas cooler/stable conditions persist over E-Europe.

DISCUSSION

... S-UK and the English Channel ...

The main story of the day will be the passage of the upper trough axis with the attendant intense depression/pressure gradient over S-UK/the English Channel.

The wind forecast is straightforward as 35-40m/s at 850hPa will mix down easily towards the surface, so damaging and potential life-threatening wind gusts affect the southern part of the UK until 18 UTC, exiting the area thereafter towards the east. Some weakening of the wind field is forecast over far SE-UK, but kinematics are still adequate for isolated extreme wind gust events.

The tornado risk is already more uncertain but most likely maximized along the coastal areas of S/SE-UK, where some onshore moisture causes marginal CAPE. Strong tornadoes will be possible, if more persistent updrafts can evolve. However this brings us to the main uncertainty: convection.

The region will be placed beneath the weakening sting jet, where intrusion of dry, high-level air and constantly evaporatively cooled airmass inhibits deep convection. This is also seen in warm EL temperature forecasts and slim convective precipitation signals. However, dry slotted areas could also see some insolation and not much BL modification is needed along the coast for deeper convective updrafts. A strong vorticity love also crosses S-UK during the daytime hours, so despite slim signals, at least supportive conditions for deep convection can't be ruled out along the coast and SE-UK.

Probably the most likely scenario will be a rapidly E/NE-ward racing forced line of convection over S-UK. Conditions onshore become worse, so the strongest activity remains confined along the south coast (probably enhanced by diurnal heating) and the level 2 was expanded inland, where the tornado risk is enhanced next to the damaging wind gust threat. As convection is forecast to play at least a partial role in this severe wind event, a level 2 became necessary. The overall risk diminishes from west to east during the day. The level-2 was expanded well towards the west, as latest data indicates a slow-down of the eastward progression of the strongest winds.






Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 01:01:00 am
id say between E - SE somewherew seem to be off wicklow mountains could be blocking though ill still keep watch

EDIT: havent seen anything yet theres a clear slot between me and those storms in the distance ive got a big Hotel complex in my way so i cant see horizon levels


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 01:11:17 am
Huge storm off Kerry coast


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 03:30:22 am
Seen an impressive night time lightning display between 02.30 and 03.00 local time from Maghera looking E and NE towards at least two storm cells a great distance away over the Irish Sea. Counted 13 intense blue flashes which reflected off the clouds in the opposite sector of sky and one amazing anvil crawler. Small clear sectors appeared in the cloud and a huge solid anvil top could be seen on the horizon lighting up. The storms where too distant for photography however the visual scene was a joy to watch. Just wish they had been closer!.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 14, 2009, 03:38:52 am
Very good that would have been cool to see, u must be in a relatively high location


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 09:25:35 am
Some heavy showers here this morning


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 02:02:16 pm
Reports coming in of a tornado in Essex


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 03:23:43 pm
Yes, Paul Sherman got images and video of the funnel, must find the quote and add it. Damage to buildings and cars from the suspected tornado also. It was either a strong multicell or supercell.  :)

From BBC...

http://news.bbc.co.uk/1/hi/england/essex/8360298.stm

From Paul...

It was exactly at 915am - Can confirm I viewed a large Horizontal Funnel Cloud (About 2 Miles in length) just North of Benfleet from the A130 (North of Saddlers Farm Roundabout) It looks like as I got onto this Storm the Tornado had just lifted, the Funnel dissipated at 0925am and the rotation spawned another Funnel Cloud North of the A127 Over the South Woodham Ferriers Area, the track of this would have been straight S-N

Not an event I will forget in a hurry for the Uk

Paul S

Here's the full quote...

Hi

I drive into London every morning for work but left 1 hour earlier due to the Lord Mayors Show starting at 1030am today, got into the car and was hearing some amazing Thunder coming from the Storm about 3-4 Miles to my West, as I drove west the precip was all to my North and North West and I was still dry, when I got onto the A127 Westbound effectively the Rain Free Area was in front of me and a Large Thick Horizontal Funnel was streched out from North to South and the Top and bottom part of this was Vertical by about 300-500feet, this suggests to me that the Tornado had just lifted from Benfleet which was 1 Mile to my South and was "roping out" by the time I stopped on a layby on the A130 North of Saddlers Farm Roundabout the funnel was now above my head and the base of the cloud was now rushing away to my north, upon looking to the North the base was now North of the A127 Over the South Woodham Ferriers area and new funnel clouds were descending, the rotation was as good as most I have seen in the USA! My only gripe is no camera was with me and if it was this would have been some of the clearest Tornado footage from the Uk as the rain area was displaced to the North East of the Storm suggesting there was Differential Updraft and Downdrafts (Eg Low Topped Supercell or Severe Multi Cell Storm)

The Tornado has literally hit a street that is under 2 Miles from my House so will go down tomorrow am and get some pictures for you all

Paul S

Video of tornadic funnel forming....

http://www.youtube.com/watch?v=eQ72qfSLoHM



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 05:51:24 pm
60 or more homes damaged according to reports from the suspected tornado.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: brianb on November 14, 2009, 06:21:47 pm
BBC R4 news (6pm) mentioned a second tornado at Lowestoft. Not aware of any confirmation or whether a line squall can be ruled out.

As for severe weather - here we got about 4mm of rainfall overnight, & the wind never even got to gale force. Sort of a semi-damp squib.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 07:03:29 pm
Thanks for the info Brian, there's mention of a 2nd tornado at that location on the UKWW but so far its true nature is unknown, and maybe a squall as you said, not enough reports in yet.

Paul Sherman who seen the tornado over Essex said it was the most remarkable UK rotation he has ever seen and even up there with some of the US tornadoes he has observed while chasing there.

Apart from the lightning show last night, which was really over the Irish Sea, it was damp squip here too, it was actually calm here all night with light to moderate rainfall so nothing to report.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 07:14:54 pm
Report from the 'Echoe'

UP to 60 homes were damaged after a suspected tornado whipped through group of Benfleet streets.

Many homes in The Lawns, The Fairway, Eversley Road, Woodside Avenue and Arundel Road lost roof tiles while a handful had chimney pots and television aerials ripped off their roofs.

Fortunately no one was hurt in the freak storm which happened at around 9.15am and lasted just seconds.

Eyewitness Adele Ashdown, 29, of The Lawns, said: “I heard a massive gale.

“The windows were shaking hard. Looking out you could see this grey swirl with lots of stuff in it.

“It was over in a second.”

Miss Ashdown lost a few roof tiles from her home but many houses were left with huge holes in their roofs.

Police closed off The Fairway, where eight homes were effected, and parts of The Lawns, Arundel Road and Seamore Avenue, for safety reasons.

Firefighters used their ariel ladder platform to help repair damaged roofs, while residents began their own clean up mission.

Car windows were smashed by flying debris and the side of a house in Woodside View was seriously damaged and will be examined by a structural engineer.

Highways Agency and Essex County Council staff were also on site within an hour to help with the clean up.

Station officer Simon Dedman said: "A severe storm hit The Fairway area of Benfleet this morning and what is believed to have been a tornado had ripped through the street and surrounding area of up to half a square mile.

“Firefighters worked professionally and their first priority was the safety of the public and then making the houses safe.

"Approximately 60 houses in total were affected, with mainly roof tiles and TV aerials coming off, eight of those houses were seriously affected with some of their roofs being blown off, fire crews made them safe using the aerial ladder platform.”

Crews from Rayleigh Weir and Basildon Fire Stations finfished making the area safe just after 1pm.



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 07:17:37 pm
Outlook for Sunday from Tony Gilbert....

(http://i34.tinypic.com/j9muef.jpg)

6pm Sat

Slight Risk of Thunderstorms perimeter regions of the UK 00Z-15Z

Slight Risk of Brief Tornado South & SE coastal regions UK 00Z-09Z

Further troughing expected to bring convective showers to coastal regions across the UK overnight and into Sunday. Deep upper trough expands to surround much of the UK increasing lapse rates. Particularly so close to relatively mild Sea Surface Temps are blown inland. Upper jet stream axis remains to the south of the UK but will influence winds enough for a time during early morning to trigger the potential for some stronger convective activity within a strong upper Positive Vorticity Max. If we look at the low level shear vertical wind profiles we can see the low end scale of brief tornado genesis for the south coast, SE and eastern coast of E.Anglia for a period 00Z-09Z. The risk will transport from west of the risk box to the eastern sector steadily through this period. Risk of tornadoes remains glued to 'coastal convergence' specifically. The risk for low level vorticity looks strong and may be ingested into and strong convective cell making landfall.

Restriction ATM for tornado geneses would seem that potential instability may not be realised as the dry tongue moves too slowly behind the surface trough.

Some uncertainties for the remainder of Sunday given limited moisture and the potential for advected mild sea air to move inland. The GFS are currently having trouble developing precip for this reason. In many ways this scenario could in fact deliver some spectacular isolated cb's as John mentioned, with hail and marginal thunder activity for a time.

The shear conditions for the remainder of Sunday will remain borderline to updraft/ downdraft separation. So probably not good to underestimate what the outlook could deliver at this point.



Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 08:58:07 pm
Here's a link to the IR sat images showing those storm anvils over the Irish Sea last night...

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=33431&posts=7&start=1


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 09:26:17 pm
Were they the cells i was looking out for lightniing last night?


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 10:24:53 pm
Yes, those are the same ones Padraig, they moved further N and I could see them from here flashing away.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 14, 2009, 10:29:14 pm
WHAT!! you have got to be high up?? ;D ;D


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 11:22:09 pm
Good point, and I forgot that Paul asked that earlier, woops I forgot....I wasn't high up at all, in fact I was in a low lying area which was quite flat which faced SE, E, and NE with a good view. I could see the lightning flashes gradually move across the sky from R to L as the storms went NE. This is why I was impressed by them, those cells must have been enormous for me to have actually seen the anvil tops at that distance.  :)

Stuart also seen a few of those flashes from Belfast around the same time.

There's storm coverage on Ch 4 news tonight showing a possible tornado/water spout over the Sea in S. Britain which apparently on youtube, I can't seem to find it though.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 14, 2009, 11:37:41 pm
http://www.channel4.com/news/articles/science_technology/storm+winds+batter+britain/3423297


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 15, 2009, 12:52:04 am
The south of England definately has seen alot of action in the last 24 hours. Bit of a disappointment here though with just a drop of rain. I see theres a few more cells trying to move up the Irish sea now could be more lightning for you to watch out for Martin  :)


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 12:56:11 am
Well spotted Paul, I have been watching those for some time now and will be watching out for more flashes. Some OK activity in the W as well. Day time on Sun might have some nice cells around W and E coastal regions.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 15, 2009, 01:00:55 am
Good stuff must keep an eye out for that


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 01:02:07 am
Yip, those are cbs with anvils to the E and W of Ireland at the min. Check out the IR sat images....

http://www.sat24.nl/gb

Worth keeping an eye on.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 01:05:30 am
Check out this report from the UKWW about the t-storm over Britain yesterday morning...

Hello all, I haven't been able to get online all day, and the people I try to talk to to don't care about the weather and it's beauty!! This morning (Saturday), at 8:40am, after getting up froma kip at 4:30am, I was woken by deep "jurassic park" rumbles of thunder, I got up and viewed out the window a non stop completely surrounding muzeum of dark, dark, furious cloud. This was followed by lots of spectacular lightning, and over 10 mins, 4 EXPLOSIONS of thunder, literally like things exploding. The hail looked like metal debris falling from the sky in perfect choreography, the winds whipped up, and then the most torrential downpour of the whole year, unbelievably LOUD, and then a humungus flash that stayed static as a light for 2 seconds, followed by an immediate B A N G, I cannot explain how loud. It's NOVEMBER, and this was the best thunder of the whole year!!!!!!!! I was looking out in anticipation for funnels, when I jumped nearly off the floor at one of these explosions that was actually thunder. It was great. Thanks for listening and reading such a long essay!!!!!!!


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: paulster78 on November 15, 2009, 01:20:10 am
Jesus that sounded like some show, It reminds me of a storm right over my old house about 15 years ago when the power was out and a similar flash of lightning very close by seemed to light up the whole countryside for a few secs, the crash of thunder came almost at the same time. At the time i think we were sure it had hit the house-Scary.  :o


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 01:20:15 am
Sferic recorded on S. coast of Ireland from NE moving coastal storms/showers.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: Padraig OBrien on November 15, 2009, 10:56:18 am
Our freinds from the isle of wight got torn apart by yesterdays storm shed roof came off tiles came off house and onto cars and their neighbours trampoline got sent through their frence


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 12:12:11 pm
Thanks for the report Padraig, yes the IOW got 100mph winds I believe, the strongest in the UK that morning.

Large cbs/storms currently in W and SW Ireland at coastal areas.


Title: Re: Possible Stormy Spell 13th to 16th Nov
Post by: martinastro on November 15, 2009, 04:53:33 pm
Tornado site investigation by Paul Sherman...

Site Investigation Conducted 9am 15th November 2009 - Benfleet Essex

I walked the entire length of the Tornado track this morning and found it to be about 1/2 Mile in Length, the damage path was no more than 50yds at it's widest. The 1st Damage was picked up near the Vicarage on Rushbottom Lane and this was quite light damage to trees, the next damage was fence panels down near Overton Road, after this the Tornado strengthened and widened to it's maximum point of about 50 yards as it hit Arundel Road (1st Pic) The Lawns (Pic 2) and the Most extensive damage in the Fairway (Pic 3,4 & 5) More Chimneys and tiles loose along Seamore Avenue and Eversley Road before the Tornado once again strengthened as it hit Fairview Crescent, the Tornado looks like it dissipated along Moreland Avenue. The Track of this Tornado was directly NE Along the entire time it was on the ground. I have spoken with many different residents including John Sullivan who lives at No 1 Fairway where the most extensive damage was and he is E-Mailing me his account later. I firmly believe this Storm dropped a further Tornado to the NE as per the previous poster stating damage in South Woodham Ferriers as I saw the occlusion above my head and lost the funnel descending into the rain to my North.

Some pictures for you all and I will leave it to the Torro Boys to determine the Strength of this event from the Pictures, my initial thoughts are T1 to T2 In strength.



Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 15, 2009, 06:26:33 pm
Edited title thread to take into account the latest outlook. More deep LPs will effect much of Ireland and UK again this week, with a low on Mon and the possibility of gales or severe gales for Wed and Thurs if the models are correct. Please keep future discussion, convective outlooks,  reports, warnings etc to this thead.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 15, 2009, 06:45:37 pm
The 12Z Models have come better into alignment, though there are still some discrepancies. Satellite imagery indicates clear development of the cold air low on the cold side of the strengthening SW Jet Core. The Jet Strengthening as a result of the sharpening upper trough moving East. The Jet likely to be exceeding 170Knts at 00Z tonight. Baroclinic zone largely remaining undeveloped lying on the warm side of the Jet, though there is a surface wave currently coming north across Biscay.

The cold air low is well forced from PVA and shear vorticity and shows a well marked cloud hook wrapping into a developing surface circulation. There remains discrepancies over the developments depth. The NAE remains the deepest with a sub 980mb centre (though a little shallower than its 06Z counterpart) over Ireland transferring NE towards S SCotland later tomorrow. The Low remaining nr 978mbs throughout the sequence. The UKMO GM has deepened the low a little more and the ECMWF is coming in between the two. The 12Z GFS is ok re its depth - but seems to be too late developing the low and has it too much to the NW on track, much prefer the track in the ECM/NAE/GM, with the ECM probably a good guess on depth. EMCWF 925mb winds do not exceed 60knts and are mostly in the 40-50Knt range - indicating gusts should be mostly nothing to worry about.

Rain comes NE, Heavy or Very Heavy across Ireland, largely Moderate elesewhere but becoming heavy across N England and in S Scotland . NAE has consistently forecasted sig totals tomorrow afternoon for the lake district with a 22mm / 6 hr value in a grid point over Keswick. It also indicates heavy rain over N Ireland tomorrow morning. ECM has highest totals over S SCotland so there remains some doubt over the exact locations of the heaviest rain also. But N Ireland, Far N England and S Scotland are the right general areas.

As we go through the week there are strong indications of a very active and mobile SW'ly becoming establisdhed but with the worst weather transferring more to the North and west. A very mild SW'ly becoming established with good indications of a classic November Warm COnveyer with potential for lots of rain in the west and north. There are lots of variations however on the rainfall detail.

Paul Blight
UKww Manager - Education/Warnings
Associate Fellow Royal Meteorological Society


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 15, 2009, 06:49:00 pm
Met Office severe weather warning for NI Mon, mainly for heavy rain with flood risk.

http://www.metoffice.gov.uk/weather/uk/ni/ni_forecast_warnings.html?day=2


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: Padraig OBrien on November 15, 2009, 09:36:12 pm
Heavy rain not too far away from me now


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 15, 2009, 11:09:01 pm
Mon outlook....

(http://i33.tinypic.com/2zge0zb.jpg)

Storm Forecast
Valid: Mon 16 Nov 2009 06:00 to Tue 17 Nov 2009 06:00 UTC
Issued: Sun 15 Nov 2009 22:22
Forecaster: SCHLENCZEK
A level 1 has been issued for Portugal and W Spain mainly for excessive rainfall and severe gusts and to a lesser extent for tornadoes.

SYNOPSIS

An upper longwave trough over the central N Atlantic will shift eastward during the period. Ahead of this trough, a 90 m/s jet streak stretches from extreme NW Iberia towards N Germany. In the vicinity of this jet streak, a developing surface low centered NW of Scotland will move northeastward. The cold front of this low will cross western France in the early morning and move eastward while weakening. Most showers and thunderstorms on Monday should be associated with the upper trough / cold front. Further upstream, a plume of warm and moist air is advected from the Canary Islands towards SW Iberia with cyclogenesis expected on Tuesday near the Bay of Biscay. An upper cold core over the Norwegian Sea will lead to unsettled conditions in parts of Scandinavia.

Most parts of southern Europe will see quiescent conditions on Monday and Tuesday as an upper ridge overspreads the western / central Mediterranean. Remnants of an upper trough over the E Mediterranean / Black Sea are forecast to shift eastward, leading to thunderstorms over the Black Sea and the E Mediterranean.

DISCUSSION

... SE Ireland, Irish Sea, British Channel, SW North Sea...

A few hundred J/kg of CAPE are forecast along the northern parts of the cold front and also near the upper cold core of the surface low near Scotland. A narrow multicell line may develop along the cold front in a strongly sheared environment (DLS around 30 m/s, LLS around 15 m/s) and an isolated severe gust cannot be ruled out. A strong gradient flow may allow some strong / severe gusts in the wake of the cold front which are mostly non-convective. Overall threat is too marginal for a level 1.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 16, 2009, 09:30:57 pm
For Tues from Tony Gilbert....

(http://i33.tinypic.com/30c403l.jpg)

Slight Risk Strong Tornado, Large Hail and Severe Gusts 15Z-18Z NW UK

Risk of strong convection over a broader area covering Ireland & UK as per map

Very strong jet stream and deep upper troughing spread east through Tues. Bowing occluded front followed by a post frontal surface trough look to trigger convective showers primarily west coastal regions of Ireland and central west UK. Whilst GFS develop CAPE offshore it is very likely that given the strong winds available that CAPE will advect inland where any developing storm cell will be able to optimise low level shear increases through surface friction.

Red box signifies the risk of stronger cell development will be possible where strong lift is generated under the front left exit region of the jet stream and intense PV max aloft. This currently aligns with with a mid level dry punch. A slight risk for strong tornadoes will occur within a short time frame! Together with a risk for large hail with a low freezing level and dry air intervention. Convective gusts are calculated at 60kts possible



Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 17, 2009, 11:23:29 am
Updated forecast, risk of severe thunderstorms and tornadoes today!

http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=33492&posts=6&mid=486389#M486389


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: Padraig OBrien on November 17, 2009, 10:55:18 pm
some models now predicting 948 mb for next saturdays storm ireland in for quite a battering this week


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: paulster78 on November 18, 2009, 09:21:07 pm
Wind has strengthened here over the last few hours but not much rain yet. The Republic has seen alot of rain again especially around the west and alot of rain forcast for tomorrow for us all.  I see the met office has a red warning out for NW England and SW Scotland, never seen that before! They're talking about maybe 250mm over the hills in that area!!  :o   


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 18, 2009, 10:56:00 pm
Winds are really picking up here now too, I expect it to get lively later tonight and Thurs. ESTOFEX are not keen on much convection from the cold front on Thurs although they do have a low risk of lightning from the eastward moving trough.

Sat's storm is still on the go although it has been downgraded slightly although gales will still affect us, it could strengthen again though, weather warnings going out over much of the country. SW Ireland will be a nasty place to be on Sat/Sun. I expect there to be a tornado risk from the front. Should be worth checking out the Moyola and River Bann by Sun for some flood photo opps  :)


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 18, 2009, 11:01:54 pm
UKww Weather Warning for Heavy rain and severe gales


Issued Wednesday 18/11/2009 0700BST

Areas affected: NW half of Wales, NW England, SW & W Scotland, N Ireland

Valid from: 0700GMT Weds 18th November - 1800GMT Fri 20th November


--------------------------------------------------------------------------------

General evolution:


The weather during this Warning period will be dominated by a major, deep (960mb Thurs 1200) Atlantic low pressure system that is drifting slowly NE towards the gap between the UK and Iceland. On its southern flank, a conveyor of warm, moist SW winds has become established and a series of frontal waves will run along this feature during the forecast period. High pressure over Europe means that a steep pressure-gradient will remain a feature throughout.


Forecast:
Wet and windy sums up the forecast with gale to severe gale-force winds causing problems at times: however, the key feature is the prolonged rainfall that will occur, pretty much continuously through towards the end of the forecast period. Latest model guidance suggests totals of 50-80mm for North Wales and, more particularly, 90-130mm for the Lake District and hills of SW Scotland: adding in a factor for enhancement over the mountains and these figures could be exceeded by 50% or more giving 150mm+ in places. The ground is already saturated so that run-off will be very high, leading to widespread standing water on roads and rivers/streams in full spate. Prone flood-plain areas are very likely to see serious flooding leading to disruption especially into the second half of the forecast period. Road travel is likely to be adversely affected and driving conditions will be hazardous throughout the period.

This forecast period ends on the evening of Friday 20th November but readers should be aware that another round of severe weather looks likely to strike over the weekend with very windy conditions a cause for concern - more on that nearer the time.

Issued by JSM for UKww, 0700GMT 18/11/2009



Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: jjb on November 18, 2009, 11:06:26 pm
I heard on the weather forecast this evening heavy rain for the north with the west expected to get 1to3 inches of rain looks like the rivers are going to be full again.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 19, 2009, 03:04:47 pm
N. Ireland today, image from BBC Newline

(http://i48.tinypic.com/ouqn4n.jpg)


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: Padraig OBrien on November 19, 2009, 10:56:54 pm
A lot of the west of ROI is  under water a lot of towns cut off not so bad here


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 20, 2009, 04:04:40 pm
Amazing and frightening looking flooding in the River Bann outside Belfast today, the river is flowing into the fields near the motorway and looks dangerous. The whole thing could turn nasty over the weekend. Couldn't get images of it from the motorway.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 20, 2009, 06:17:36 pm
The severe floods in Britain and Cork are horrific, sorry to hear about the death of a police officer when the bridge he was standing collapsed in the terrible flood. Very sad.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: paulster78 on November 20, 2009, 07:26:52 pm
Yeah thats a tragedy.  Cumbria has had un unbelievable amount of rain, record-breaking i think.  Galway is very badly affected too and nearer home lough Erne continues to rise from runoff and alot of roads are impassable in Fermanagh.  Might try and get some images from here over the weekend.


Title: Re: Possible Stormy Spell 13th to 19th Nov
Post by: martinastro on November 20, 2009, 07:46:56 pm
I hear there's some bad flooding in parts of NI now too.

Met Office called the Cumbrian extreme flood a 1 in 1000 year event!. The video footage is sobering.

Will keep the camera close to hand over the next few days.